The broad, long term objectives of this proposal are to understand the physical and biological mechanisms for the immediate, long-term tumor regression generated after the electrically mediated delivery of non-coding, bacterially derived plasmid DNA. This effect requires neither therapeutic cDNA expression nor eukaryotic sequences within plasmids. The specific aims of this proposal are to test two hypotheses: The electroporation parameters for delivery of non-coding DNA can be manipulated to minimize the quantity of electricity delivered while maintaining efficient induction of tumor regression. The immediate tumor regression is due to a combination of the induction of apoptosis or necrosis and the induction of an immune response. This research derives its health relatedness from the possible use of this effect as a cancer therapy, as well as the possible consequences of this antitumor effect on electrically mediated therapeutic gene delivery in general. The research is designed to determine (a) which particular electroporation parameters are necessary to generate this strong antitumor effect, (b) if apoptosis and an induced immune response are responsible for tumor regression, (c) a possible signaling cascade, and (d) the immune cells and cytokines involved in the tumor regression process. The methods used include the manipulation of the electrical parameters and electrodes involved in the delivery, histological analysis to confirm the presence of apoptosis, and microarray analysis to implicate a possible signaling cascade. Specific antitumor immune mechanisms will be explored. The studies described in this proposal will characterize this effect and may have significant application for the development of efficacious gene delivery methods through electroporation that mediate clinically relevant antitumor responses. [unreadable] [unreadable]